The thermal structure of the stratosphere and ionosphere is more elaborate than has heretofore been assumed. No appreciable rise in temperature up to 30 km is indicated from direct observations. A temperature of + 50°C at a height of 50 km is supported by the results on anomalous sound propagation, and of research on ozone and meteors, as well as by the theory of atmospheric tides. At heights around 50 to 80 km, the temperature again falls to −70°C, and afterwards rises again to somewhere between + 60°C and + 160°C at a height of 100 km. At heights around 200 to 250 km, the temperature is probably between + 160°C and + 560°C. In the polar regions at 100 km, the temperature is about −40°C, showing the marked difference due to latitude. A new definition for the concept of temperature in the upper atmosphere is given, since allowance must be made for radiation density.
* This is an important and competent review of knowledge on this subject up to 1941, and we have not seen a later survey of this type in print.—Ed.